1. Field of the Invention
This invention relates generally to a quality control process and more particularly to a quality control process for use in lumber-cutting operations.
2. Description of the Prior Art
In sawmill operations it is customary to first debark a raw log, then saw or rip the log in a lengthwise direction into the desired board sizes, and finally to transversely crosscut the board into shortened lengths where necessary to remove defects in the board. This crosscutting operation is typically performed last, since the defects may not be visible until the final longitudinal rip is performed.
The crosscutting operation is critical since it is essential that all substantial defects in the board be removed; yet, it is also essential that the longest lengths possible be left for sale. In order to be able to produce optimum board lengths, the sawyer must be intimately familiar with the type of board defects which will have an adverse effect upon the appearance and/or performance of the boards. Defects, such as wane edges, blue stain, pitch seams, knotholes, cross grain, and rot or incipient decay, must almost always be removed. The sawyer's utmost attention and skill is necessary in order to make the correct determination as to which defects should be removed, and precisely the way in which they should be removed, so that the highest possible percentage of the board is retained.
In the past, it has been difficult to monitor and evaluate the work of a sawyer. This is due to the fact that there normally are several such sawyers working in any particular lumber cutting operation; so there is no way of evaluating, from the commingled pieces of lumber, the quality of cuts made by any particular sawyer. The use of an observer is expensive and ineffective, since the operator is normally aware of the observance and therefore often has a tendency to perform the work with an artificially high degree of skill and conscientiousness for the length of time observed. Permanent observation would be cost prohibitive.
A second method which might be used to qualitatively evaluate the work of the sawyers is to provide the saws of each of the sawyers with a distinctive stamp which identifies each piece of wood which is cut with the saw. This at least theoretically makes it possible to determine the quantity of work being done by a sawyer. However, qualitative analysis is impractical because by the time the boards from a particular sawyer are capable of collection, they are normally commingled with many other boards also cut by the same sawyer. Thus, it would be exceedingly difficult and clearly uneconomical to reassemble the boards to effectively determine the efficiency of the lumber-cutting operations.
A different approach which has been taken to optimize the efficiency of defect removal has been to remove the human element entirely by utilizing a computer which scans the boards with a laser. Since defects have a greater than normal tendency to reflect the laser, identification of defects is possible. Such systems have not been totally satisfactory because some critical defects are of the type that do not return laser light in sufficient quantities to be recognized by the system. Also, superficial dirt or similar markings on the wood may appear as defects to the laser scanner. This results in unnecessary cuts being taken, which could have a substantial effect upon the efficiency of the lumber-cutting operation. Even if it is assumed that such technical problems will be overcome in the future, the cost of this type of system is likely to continue to be very high, well beyond the means of smaller operators.
Hence, it is a primary object of the present invention to provide an improved quality control process which effectively and reliably overcomes the aforementioned limitations and drawbacks of the prior art proposals. More specifically, the present invention has as its objects one or more of the following, taken individually or in combination:
(1) To provide a process for quality control in lumber-cutting operations in which the sawyer can be monitored without his knowledge, thereby providing an accurate indication of the quality of work being performed;
(2) The provision of quality control process which can be economically implemented on a periodic basis without interrupting commercial operations;
(3) To provide a process in which the work of lumber-cutting personnel can be evaluated which does not require complex equipment or extensive training of personnel and which is readily adaptable to conventional lumber-cutting operations; and
(4) To develop a quality control process which will improve the efficiency of a lumber-cutting operation, thereby increasing profits and/or lowering prices, while at the same time conserving valuable natural resources.